Acute and chronic effects of continuous positive airway pressure therapy on left ventricular systolic and diastolic function in patients with obstructive sleep apnea and congestive heart failure

BACKGROUND:

Obstructive sleep apnea (OSA) may contribute to the pathogenesis of congestive heart failure (CHF). Nocturnal continuous positive airway pressure (CPAP) therapy can alleviate OSA and may have a role in the treatment of CHF patients.

OBJECTIVES:

To investigate the acute and chronic effects of CPAP therapy on left ventricular systolic function, diastolic function and filling pressures in CHF patients with OSA.

METHODS:

Twelve patients with stable CHF (New York Heart Association II or III, radionuclide ejection fraction lower than 40%) underwent overnight polysomnography to detect OSA. In patients with OSA (n=7), echocardiography was performed at baseline (awake, before and during acute CPAP administration) and after 6.9±3.3 weeks of nocturnal CPAP therapy. Patients without OSA (n=5) did not receive CPAP therapy, but underwent a baseline and follow-up echocardiogram.

RESULTS:

In CHF patients with OSA, acute CPAP administration resulted in a decrease in stroke volume (44±15 mL versus 50±14 mL, P=0.002) and left ventricular ejection fraction ([LVEF] 34.8±5.0% versus 38.4±3.3%, P=0.006) compared with baseline, but no change in diastolic function or filling pressures (peak early diastolic mitral annular velocity [Ea]: 6.0±1.6 cm/s versus 6.3±1.6 cm/s, P not significant; peak early filling velocity to peak late filling velocity [E/A] ratio: 1.05±0.74 versus 1.00±0.67, P not significant; E/Ea ratio: 10.9±4.1 versus 11.3±4.1, P not significant). In contrast, chronic CPAP therapy resulted in a trend to an increase in stroke volume (59±19 mL versus 50±14 mL, P=0.07) and a significant increase in LVEF (43.4±4.8% versus 38.4±3.3%, P=0.01) compared with baseline, but no change in diastolic function or filling pressures (Ea: 6.2±1.2 cm/s versus 6.3±1.6 cm/s, P not significant; E/A ratio: 1.13±0.61 versus 1.00±0.67, P not significant; E/Ea ratio: 12.1±2.7 versus 11.3±4.1, P not significant). There was no change in left ventricular systolic function, diastolic function or filling pressures at follow-up in CHF patients without OSA.

CONCLUSIONS:

Acute CPAP administration decreased stroke volume and LVEF in stable CHF patients with OSA. In contrast, chronic CPAP therapy for seven weeks improved left ventricular systolic function, but did not affect diastolic function or filling pressures. The potential clinical implications of the discrepant effects of CPAP therapy on left ventricular systolic and diastolic function in CHF patients with OSA warrant further study.     

Functional Vascular Study in Hypertensive Subjects with Type 2 Diabetes Using Losartan or Amlodipine

Background

Antihypertensive drugs are used to control blood pressure (BP) and reduce macro- and microvascular complications in hypertensive patients with diabetes.

Objectives

The present study aimed to compare the functional vascular changes in hypertensive patients with type 2 diabetes mellitus after 6 weeks of treatment with amlodipine or losartan.

Methods

Patients with a previous diagnosis of hypertension and type 2 diabetes mellitus were randomly divided into 2 groups and evaluated after 6 weeks of treatment with amlodipine (5 mg/day) or losartan (100 mg/day). Patient evaluation included BP measurement, ambulatory BP monitoring, and assessment of vascular parameters using applanation tonometry, pulse wave velocity (PWV), and flow-mediated dilation (FMD) of the brachial artery.

Results

A total of 42 patients were evaluated (21 in each group), with a predominance of women (71%) in both groups. The mean age of the patients in both groups was similar (amlodipine group: 54.9 ± 4.5 years; losartan group: 54.0 ± 6.9 years), with no significant difference in the mean BP [amlodipine group: 145 ± 14 mmHg (systolic) and 84 ± 8 mmHg (diastolic); losartan group: 153 ± 19 mmHg (systolic) and 90 ± 9 mmHg (diastolic)]. The augmentation index (30% ± 9% and 36% ± 8%, p = 0.025) and augmentation pressure (16 ± 6 mmHg and 20 ± 8 mmHg, p = 0.045) were lower in the amlodipine group when compared with the losartan group. PWV and FMD were similar in both groups.

Conclusions

Hypertensive patients with type 2 diabetes mellitus treated with amlodipine exhibited an improved pattern of pulse wave reflection in comparison with those treated with losartan. However, the use of losartan may be associated with independent vascular reactivity to the pressor effect.     

Noninvasive ventilation initiation in clinical practice: A six-year prospective, observational study

BACKGROUND:

Despite evidence supporting the role of noninvasive ventilation (NIV) in diverse populations, few publications describe how NIV is used in clinical practice.

OBJECTIVE:

To describe NIV initiation in a teaching hospital that has a guideline, and to characterize temporal changes in NIV initiation over time.

METHODS:

A prospective, observational study of continuous positive airway pressure ventilation (CPAP) or bilevel NIV initiation from January 2000 to December 2005 was conducted. Registered respiratory therapists completed a one-page data collection form at NIV initiation.

RESULTS:

Over a six-year period, NIV was initiated in 623 unique patients (531 bilevel NIV, 92 CPAP). Compared with bilevel NIV, CPAP was initiated more often using a nasal interface, with a machine owned by the patient, and for chronic conditions, especially obstructive sleep apnea. Whereas CPAP was frequently initiated and continued on the wards, bilevel NIV was most frequently initiated and continued in the emergency department, intensive care unit and the coronary care unit. Patients initiated on bilevel NIV were more likely to be female (OR 1.8, 95% CI 1.08 to 2.85; P=0.02) and to have an acute indication compared with CPAP initiations (OR 7.5, 95% CI 1.61 to 34.41; P=0.01). Bilevel NIV was initiated more often in the emergency department than in the intensive care unit (OR 5.8, 95% CI 0.89 to 38.17; P=0.07). Bilevel NIV initiation increased from 2000 to 2005.

CONCLUSIONS:

The present study illustrates how NIV is used in clinical practice and confirms that NIV initiation has increased over time.     

Noninvasive ventilation practice patterns for acute respiratory failure in Canadian tertiary care centres: A descriptive analysis

BACKGROUND:

The extent of noninvasive ventilation (NIV) use for patients with acute respiratory failure in Canadian hospitals, indications for use and associated outcomes are unknown.

OBJECTIVE:

To describe NIV practice variation in the acute setting.

METHODS:

A prospective observational study involving 11 Canadian tertiary care centres was performed. Data regarding NIV indication, mode and outcomes were collected for all adults (>16 years of age) treated with NIV for acute respiratory failure during a four-week period (between February and August 2011). Logistic regression with site as a random effect was used to examine the association between preselected predictors and mortality or intubation.

RESULTS:

A total of 330 patients (mean [± SD] 30±12 per centre) were included. The most common indications for NIV initiation were pulmonary edema (104 [31.5%]) and chronic obstructive pulmonary disease (99 [30.0%]). Significant differences in indications for NIV use across sites, specialty of ordering physician and location of NIV initiation were noted. Although intubation rates were not statistically different among sites (range 10.3% to 45.4%), mortality varied significantly (range 6.7% to 54.5%; P=0.006). In multivariate analysis, the most significant independent predictor of avoiding intubation was do-not-resuscitate status (OR 0.11 [95% CI 0.03 to 0.37]).

CONCLUSION:

Significant variability existed in NIV use and associated outcomes among Canadian tertiary care centres. Assignment of do-not-resuscitate status prevented intubation.     

Do obstructive sleep apnea syndrome patients underestimate their daytime symptoms before continuous positive airway pressure treatment?

BACKGROUND:

Daytime somnolence is an important feature of the obstructive sleep apnea (OSA) hypopnea syndrome and is usually subjectively assessed using the Epworth Sleepiness Scale (ESS).

OBJECTIVE:

To compare the scores of the ESS and different domains of the Quebec Sleep Questionnaire (QSQ) assessed before and after the first months of continuous positive airway pressure (CPAP) treatment, as well as retrospectively without treatment.

METHODS:

The ESS score and domain scores of the QSQ were obtained before and after a three-month period of CPAP treatment using a retrospective assessment of the pretreatment scores in 76 untreated OSA patients.

RESULTS:

Fifty-two patients completed the study. The ESS and QSQ scores significantly improved following CPAP therapy. Retrospective evaluation of the ESS score was significantly worse than pre- and post-treatment values (mean [± SD] pretreatment score 11.0±4.8; retrospective pretreatment score 13.5±5.1). Such differences were not observed in any domain of the QSQ, including the domain assessing hypersomnolence.

CONCLUSION:

OSA patients underestimated their sleepiness according to the most widely used instrument to assess hypersomnolence. This finding may not be observed with other methods used to assess OSA-related symptoms such as quality of life questionnaires.     

Cardiac I123-MIBG Correlates Better than Ejection Fraction with Symptoms Severity in Systolic Heart Failure

Background

The association of autonomic activation, left ventricular ejection fraction (LVEF) and heart failure functional class is poorly understood.

Objective

Our aim was to correlate symptom severity with cardiac sympathetic activity, through iodine-123-metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy and with LVEF in systolic heart failure (HF) patients without previous beta-blocker treatment.

Methods

Thirty-one patients with systolic HF, class I to IV of the New York Heart Association (NYHA), without previous beta-blocker treatment, were enrolled and submitted to ¹²³I-MIBG scintigraphy and to radionuclide ventriculography for LVEF determination. The early and delayed heart/mediastinum (H/M) ratio and the washout rate (WR) were performed.

Results

According with symptom severity, patients were divided into group A, 13 patients in NYHA class I/II, and group B, 18 patients in NYHA class III/IV. Compared with group B patients, group A had a significantly higher LVEF (25% ± 12% in group B vs. 32% ± 7% in group A, p = 0.04). Group B early and delayed H/M ratios were lower than group A ratios (early H/M 1.49 ± 0.15 vs. 1.64 ± 0.14, p = 0.02; delayed H/M 1.39 ± 0.13 vs. 1.58 ± 0.16, p = 0.001, respectively). WR was significantly higher in group B (36% ± 17% vs. 30% ± 12%, p= 0.04). The variable that showed the best correlation with NYHA class was the delayed H/M ratio (r= -0.585; p=0.001), adjusted for age and sex.

Conclusion

This study showed that cardiac ¹²³I-MIBG correlates better than ejection fraction with symptom severity in systolic heart failure patients without previous beta-blocker treatment.     

Linking soluble vascular adhesion molecule-1 level to calcific aortic stenosis in patients with coronary artery disease

BACKGROUND:

Calcific aortic stenosis (AS) is an atherosclerosis-related process and the most common cause of valve disease requiring surgery.

OBJECTIVE:

To assess the association of inflammatory markers with AS in advanced atherosclerosis.

METHODS:

Consecutive patients with coronary artery disease (CAD) associated with AS were prospectively identified (mean transvalvular aortic gradient of 30 mmHg or greater). Subjects with aortic sclerosis (mean transvalvular aortic gradient of 10 mmHg or less) served as controls. All patients underwent clinical evaluation, echocardiography and coronary angiography.

RESULTS:

One hundred twenty-two patients with AS (85 men) and 101 with aortic sclerosis (76 men) of similar CAD severity were enrolled. The AS patients were older (mean [± SD] 71±7 years versus 66±7 years; P<0.001), had higher soluble vascular adhesion molecule-1 (s-VCAM-1) levels (1533±650 μg/L versus 1157±507 μg/L; P<0.001), but lower soluble intercellular adhesion molecule-1 (s-ICAM-1) (254±81 μg/L versus 293±84 μg/L; P<0.01) and soluble E-selectin (53±28 μg/L versus 62±29 μg/L; P<0.05) levels. The two groups did not differ with respect to C-reactive protein level (3±2.9 mg/L versus 3.4±2.6 mg/L; P not significant). Higher s-VCAM-1 (OR 1.09, 95% CI 1.04 to 1.14; P<0.001) and lower s-ICAM-1 (OR 0.82, 95% CI 0.72 to 0.94; P<0.001) levels were associated with AS after adjustment for age.

CONCLUSION:

Increased s-VCAM-1 levels were associated with calcific AS in patients with significant CAD.     

Initial Experience of Two National Centers in Transcatheter Aortic Prosthesis Implantation

Background

Transcatheter aortic valve implantation is an effective alternative to surgical treatment of severe aortic stenosis in patients who are inoperable or at high surgical risk.

Objectives

To report the immediate and follow-up clinical and echocardiographic results of the initial experience of transcatheter aortic valve implantation.

Methods

From 2009 June to 2013 February, 112 patients underwent transcatheter aortic valve implantation.

Results

Mean age was 82.5 ± 6.5 years, and the logistic EuroSCORE was 23.6 ± 13.5. Procedural success was 84%. After the intervention, a reduction in the mean systolic gradient was observed (pre: 54.7 ± 15.3 vs. post: 11.7 ± 4.0 mmHg; p < 0.01). Cerebrovascular accidents occurred in 3.6%, vascular complications in 19% and permanent pacemaker was required by 13% of the patients. Thirty-day mortality and at follow-up of 16 ± 11 months was 14% and 8.9% respectively. The presence of chronic obstructive pulmonary disease was the only predictor of mortality at 30 days and at follow-up. During follow up, aortic valve area and mean systolic gradient did not change significantly.

Conclusions

Transcatheter aortic valve implantation is an effective and safe procedure for the treatment of aortic stenosis in high-surgical risk or inoperable patients. The presence of chronic obstructive pulmonary disease was the only independent predictor of mortality identified both in the first month post-intervention and at follow-up.     

Left atrial size and force in patients with systolic chronic heart failure: Comparison with healthy controls and different cardiac diseases

BACKGROUND:

Left atrial (LA) systolic force (LASF) is significantly increased in chronic heart failure (CHF), arterial hypertension (HT) and aortic stenosis (AS). The increase is proportional to the degree of left ventricular hypertrophy and diastolic dysfunction.

OBJECTIVES:

To assess the magnitude of changes in maximal LA volume (LAV_max) and LASF in systolic CHF compared with other cardiac diseases, and to assess whether the left atrium remodels differently and works in response to specific conditions affecting diastolic function and to individual factors associated with LA alterations.

METHODS:

LAV_max and LASF were measured and evaluated by two-dimensional Doppler echocardiography in 94 patients with systolic CHF and normal left ventricular filling pressure, 100 control patients, 181 patients with HT, 40 patients with idiopathic hypertrophic cardiomyopathy (HCMP) and 85 patients with AS. The prevalence of LA dilation and supernormal LASF (defined as values of LAV_max and LASF exceeding two SDs of the mean of controls) was measured in all groups.

RESULTS:

LAV_max and LASF were 7.1±2 mL/m³ and 7.8±4 kdynes in controls, and 11.0±4 mL/m³ and 19.7±11 kdynes in systolic CHF patients, respectively (both P<0.001). These values were significantly higher than in patients with HT, but similar to those with AS and HCMP. LA dilation and supernormal LASF were detected in 13% and 11% of patients with HT, 32% and 59% of patients with AS, 26% and 43% of patients with HCMP, and 41% and 56% of patients with systolic CHF, respectively (all P<0.01). In multiple logistic analysis, systolic CHF represented the strongest predictor of supernormal LASF. It was not independently associated with LA dilation, which was mainly related to indexes of volume load.

CONCLUSIONS:

LAV_max and LASF were markedly increased in patients with systolic CHF, with a magnitude that was significantly higher than that of HT patients, but similar to that measured in HCMP and AS patients. In the present community population with various cardiac diseases, systolic CHF represented the most powerful stimulus for increasing LASF and was not related to LA dilation.     

Ivabradine Improves Heart Rate Variability in Patients with Nonischemic Dilated Cardiomyopathy

Background

Ivabradine is a novel specific heart rate (HR)-lowering agent that improves event-free survival in patients with heart failure (HF).

Objectives

We aimed to evaluate the effect of ivabradine on time domain indices of heart rate variability (HRV) in patients with HF.

Methods

Forty-eight patients with compensated HF of nonischemic origin were included. Ivabradine treatment was initiated according to the latest HF guidelines. For HRV analysis, 24-h Holter recording was obtained from each patient before and after 8 weeks of treatment with ivabradine.

Results

The mean RR interval, standard deviation of all normal to normal RR intervals (SDNN), the standard deviation of 5-min mean RR intervals (SDANN), the mean of the standard deviation of all normal-to-normal RR intervals for all 5-min segments (SDNN index), the percentage of successive normal RR intervals exceeding 50 ms (pNN50), and the square root of the mean of the squares of the differences between successive normal to normal RR intervals (RMSSD) were low at baseline before treatment with ivabradine. After 8 weeks of treatment with ivabradine, the mean HR (83.6 ± 8.0 and 64.6 ± 5.8, p < 0.0001), mean RR interval (713 ± 74 and 943 ± 101 ms, p < 0.0001), SDNN (56.2 ± 15.7 and 87.9 ± 19.4 ms, p < 0.0001), SDANN (49.5 ± 14.7 and 76.4 ± 19.5 ms, p < 0.0001), SDNN index (24.7 ± 8.8 and 38.3 ± 13.1 ms, p < 0.0001), pNN50 (2.4 ± 1.6 and 3.2 ± 2.2 %, p < 0.0001), and RMSSD (13.5 ± 4.6 and 17.8 ± 5.4 ms, p < 0.0001) substantially improved, which sustained during both when awake and while asleep.

Conclusion

Our findings suggest that treatment with ivabradine improves HRV in nonischemic patients with HF.     

Effectiveness of phosphodiesterase-5 inhibitor therapy for portopulmonary hypertension

BACKGROUND:

Portopulmonary hypertension is associated with significant morbidity and mortality. Phosphodiesterase-5 inhibitor therapy is efficacious in other causes of WHO group I pulmonary arterial hypertension.

OBJECTIVE:

To evaluate the efficacy and safety of phosphodiesterase-5 inhibitor therapy in patients with portopulmonary hypertension.

METHODS:

A single-centre retrospective cohort study that included patients with a diagnosis of portopulmonary hypertension was performed. The primary outcome was change in pulmonary vascular resistance after six months of phosphodiesterase-5 inhibitor therapy. A secondary evaluation investigated the effect on other hemodynamic measurements, 6 min walk distance, functional class, safety outcomes and survival.

RESULTS:

Of 1385 patients screened, 25 patients with portopulmonary hypertension were identified, of whom 20 received a phosphodiesterase-5 inhibitor. After six months, there was a significant decrease in pulmonary vascular resistance (−236 dyn·s·cm⁻⁵ [95% CI −343 dyn·s·cm⁻⁵ to −130 dyn·s·cm⁻⁵]; P<0.001), mean pulmonary artery pressure (−8.9 mmHg [95% CI −13.7 mmHg to −4.2 mmHg]; P=0.001) and an increase in Fick cardiac output (0.9 L/min [95% CI 0.1 L/min to 1.6 L/min]; P=0.02). There was no change in 6 min walk distance. The proportion of subjects with a WHO functional class III or IV was significantly reduced at six months compared with baseline (18% versus 61%; P=0.002). Safety outcomes did not reveal any adverse events.

CONCLUSIONS:

Phosphodiesterase-5 inhibitor therapy improved hemodynamics and functional class at six months in a cohort of patients with portopulmonary hypertension.     

Heart Rate Recovery in the First Minute at the Six-Minute Walk Test in Patients with Heart Failure

Background

Heart rate recovery at one minute of rest (HRR₁) is a predictor of mortality in heart failure (HF), but its prognosis has not been assessed at six-minute walk test (6MWT) in these patients.

Objective

This study aimed to determine the HRR₁ at 6MWT in patients with HF and its correlation with six-minute walk distance (6MWD).

Methods

Cross-sectional, controlled protocol with 161 individuals, 126 patients with stable systolic HF, allocated into 2 groups (G1 and G2) receiving or not β-blocker and 35 volunteers in control group (G3) had HRR₁ recorded at the 6MWT.

Results

HRR₁ and 6MWD were significantly different in the 3 groups. Mean values of HRR₁ and 6MWD were: HRR₁ = 12 ± 14 beat/min G1; 18 ± 16 beat/min G2 and 21 ± 13 beat/min G3; 6MWD = 423 ± 102 m G1; 396 ± 101m G2 and 484 ± 96 m G3 (p < 0.05). Results showed a correlation between HRR₁ and 6MWD in G1(r = 0.3; p = 0.04) and in G3(r = 0.4; p= 0.03), but not in G2 (r= 0.12; p= 0.48).

Conclusion

HRR₁ response was attenuated in patients using βB and showed correlation with 6MWD, reflecting better exercise tolerance. HRR₁ after 6MWT seems to represent an alternative when treadmill tests could not be tolerated.     

Increased QT dispersion and P wave dispersion in major depressive disorder

BACKGROUND:

QT and P wave dispersion parameters can indicate abnormalities in autonomic nervous system and cardiac functioning.

OBJECTIVES:

To determine QT and P wave dispersion in patients with major depressive disorder compared with healthy volunteers.

METHODS:

Fifty newly diagnosed patients with major depressive disorder and 50 age- and sex-matched healthy volunteers underwent 12-lead electrocardiography. QT interval, QT dispersion, heart rate-corrected QT dispersion and P wave dispersions were calculated manually by a blinded specialist.

RESULTS:

Groups were comparable in terms of age, sex, body mass index, smoking status, metabolic diseases and left ventricular ejection fraction. The major depressive disorder group had significantly higher QT dispersion (58.5±9.9 versus 41.7±3.8; P<0.001), heart rate-corrected QT dispersion (62.5±10.0 versus 45.2±4.3; P<0.001) and P wave dispersion (46.9±4.8 versus 41.5±5.1; P<0.001).

CONCLUSION:

Increased QT dispersion, heart-rate corrected QT dispersion and P wave dispersion in major depressive disorder patients may be indicative of autonomic imbalance and increased risk of cardiac morbidity and mortality.     

Atrial Fibrillation Ablation in Systolic Dysfunction: Clinical and Echocardiographic Outcomes

Background

Heart failure and atrial fibrillation (AF) often coexist in a deleterious cycle.

Objective

To evaluate the clinical and echocardiographic outcomes of patients with ventricular systolic dysfunction and AF treated with radiofrequency (RF) ablation.

Methods

Patients with ventricular systolic dysfunction [ejection fraction (EF) <50%] and AF refractory to drug therapy underwent stepwise RF ablation in the same session with pulmonary vein isolation, ablation of AF nests and of residual atrial tachycardia, named "background tachycardia". Clinical (NYHA functional class) and echocardiographic (EF, left atrial diameter) data were compared (McNemar test and t test) before and after ablation.

Results

31 patients (6 women, 25 men), aged 37 to 77 years (mean, 59.8±10.6), underwent RF ablation. The etiology was mainly idiopathic (19 p, 61%). During a mean follow-up of 20.3±17 months, 24 patients (77%) were in sinus rhythm, 11 (35%) being on amiodarone. Eight patients (26%) underwent more than one procedure (6 underwent 2 procedures, and 2 underwent 3 procedures). Significant NYHA functional class improvement was observed (pre-ablation: 2.23±0.56; postablation: 1.13±0.35; p<0.0001). The echocardiographic outcome also showed significant ventricular function improvement (EF pre: 44.68%±6.02%, post: 59%±13.2%, p=0.0005) and a significant left atrial diameter reduction (pre: 46.61±7.3 mm; post: 43.59±6.6 mm; p=0.026). No major complications occurred.

Conclusion

Our findings suggest that AF ablation in patients with ventricular systolic dysfunction is a safe and highly effective procedure. Arrhythmia control has a great impact on ventricular function recovery and functional class improvement.     

Benefit of a low-fat over high-fat diet on vascular health during alternate day fasting

Background:

Alternate day fasting (ADF) with a low-fat (LF) diet improves brachial artery flow-mediated dilation (FMD). Whether these beneficial effects can be reproduced with a high-fat (HF) diet remains unclear.

Objective:

This study compared the effects of ADF-HF to ADF-LF regimens on FMD. The role that adipokines have in mediating this effect was also investigated.

Methods:

Thirty-two obese subjects were randomized to an ADF-HF (45% fat) or ADF-LF diet (25% fat), consisting of two phases: (1) a 2-week baseline weight maintenance period and (2) an 8-week ADF weight loss period. Food was provided throughout the study.

Results:

Body weight was reduced (P<0.0001) in the ADF-HF (4.4±1.0 kg) and ADF-LF group (3.7±0.7 kg). FMD decreased (P<0.05) by ADF-HF relative to baseline (7±1 to 5±2%) and increased (P<0.05) by ADF-LF (5±1 to 7±2%). Blood pressure remained unchanged in both groups. Adiponectin increased (P<0.05) in the ADF-HF (43±7%) and ADF-LF group (51±7%). Leptin and resistin decreased (P<0.05) in the ADF-HF (32±5% 23±5%) and ADF-LF group (30±3% 27±4%). Increases in adiponectin were associated with augmented FMD in the ADF-LF group only (r=0.34, P=0.03).

Conclusion:

Thus, improvements in FMD with ADF may only occur with LF diets and not with HF diets, and adipokines may not have a significant role in mediating this effect.     

Impact of the metabolic syndrome on aortic pulse pressure and ascending aortic pulsatility in patients with angiographically normal coronary arteries

BACKGROUND:

Large artery stiffness is a major determinant of pulse pressure (PP), and PP at baseline has been associated with future coronary events.

OBJECTIVE:

To evaluate the impact of the metabolic syndrome on aortic PP and ascending aortic pulsatility (AP) in patients with angiographically normal coronary arteries.

METHODS:

Forty-two patients with the metabolic syndrome and 40 age-matched control subjects without the metabolic syndrome were included in the study. All subjects had normal coronary arteries. Diagnosis of the metabolic syndrome was based on the International Diabetes Federation guidelines published in 2005. Ascending AP was estimated as the ratio of aortic PP to mean blood pressure.

RESULTS:

Aortic PP (59±12 mmHg versus 43±10 mmHg; P<0.001) and ascending AP (0.54±0.10 versus 0.48±0.10; P<0.001) were significantly higher in the metabolic syndrome group. Multiple regression analysis revealed statistically independent relationships between ascending AP and fasting blood glucose, waist circumference and systolic blood pressure (model R²=0.408; P<0.001). The metabolic syndrome, as a whole, was also independently associated with both ascending AP (P<0.01) and aortic PP (P<0.01).

CONCLUSION:

The data showed that the metabolic syndrome is independently associated with increased aortic PP and ascending AP in patients with normal coronary arteries, suggesting aortic stiffness as one of the possible mechanisms underlying the excess cardiovascular risk associated with the metabolic syndrome.     

Cardiovascular Autonomic Dysfunction in Patients with Morbid Obesity

Background

Morbid obesity is directly related to deterioration in cardiorespiratory capacity, including changes in cardiovascular autonomic modulation.

Objective

This study aimed to assess the cardiovascular autonomic function in morbidly obese individuals.

Methods

Cross-sectional study, including two groups of participants: Group I, composed by 50 morbidly obese subjects, and Group II, composed by 30 nonobese subjects. The autonomic function was assessed by heart rate variability in the time domain (standard deviation of all normal RR intervals [SDNN]; standard deviation of the normal R-R intervals [SDNN]; square root of the mean squared differences of successive R-R intervals [RMSSD]; and the percentage of interval differences of successive R-R intervals greater than 50 milliseconds [pNN50] than the adjacent interval), and in the frequency domain (high frequency [HF]; low frequency [LF]: integration of power spectral density function in high frequency and low frequency ranges respectively). Between-group comparisons were performed by the Student’s t-test, with a level of significance of 5%.

Results

Obese subjects had lower values of SDNN (40.0 ± 18.0 ms vs. 70.0 ± 27.8 ms; p = 0.0004), RMSSD (23.7 ± 13.0 ms vs. 40.3 ± 22.4 ms; p = 0.0030), pNN50 (14.8 ± 10.4 % vs. 25.9 ± 7.2%; p = 0.0061) and HF (30.0 ± 17.5 Hz vs. 51.7 ± 25.5 Hz; p = 0.0023) than controls. Mean LF/HF ratio was higher in Group I (5.0 ± 2.8 vs. 1.0 ± 0.9; p = 0.0189), indicating changes in the sympathovagal balance. No statistical difference in LF was observed between Group I and Group II (50.1 ± 30.2 Hz vs. 40.9 ± 23.9 Hz; p = 0.9013).

Conclusion

morbidly obese individuals have increased sympathetic activity and reduced parasympathetic activity, featuring cardiovascular autonomic dysfunction.     

Resistance Exercise Restores Endothelial Function and Reduces Blood Pressure in Type 1 Diabetic Rats

Background

Resistance exercise effects on cardiovascular parameters are not consistent.

Objectives

The effects of resistance exercise on changes in blood glucose, blood pressure and vascular reactivity were evaluated in diabetic rats.

Methods

Wistar rats were divided into three groups: control group (n = 8); sedentary diabetic (n = 8); and trained diabetic (n = 8). Resistance exercise was carried out in a squat device for rats and consisted of three sets of ten repetitions with an intensity of 50%, three times per week, for eight weeks. Changes in vascular reactivity were evaluated in superior mesenteric artery rings.

Results

A significant reduction in the maximum response of acetylcholine-induced relaxation was observed in the sedentary diabetic group (78.1 ± 2%) and an increase in the trained diabetic group (95 ± 3%) without changing potency. In the presence of NG-nitro-L-arginine methyl ester, the acetylcholine-induced relaxation was significantly reduced in the control and trained diabetic groups, but not in the sedentary diabetic group. Furthermore, a significant increase (p < 0.05) in mean arterial blood pressure was observed in the sedentary diabetic group (104.9 ± 5 to 126.7 ± 5 mmHg) as compared to that in the control group. However, the trained diabetic group showed a significant decrease (p < 0.05) in the mean arterial blood pressure levels (126.7 ± 5 to 105.1 ± 4 mmHg) as compared to the sedentary diabetic group.

Conclusions

Resistance exercise could restore endothelial function and prevent an increase in arterial blood pressure in type 1 diabetic rats.     

Human Tissue Kallikrein Activity in Angiographically Documented Chronic Stable Coronary Artery Disease

Background

Human tissue kallikrein (hK1) is a key enzyme in the kallikrein–kinin system (KKS). hK1-specific amidase activity is reduced in urine samples from hypertensive and heart failure (HF) patients. The pathophysiologic role of hK1 in coronary artery disease (CAD) remains unclear.

Objective

To evaluate hK1-specific amidase activity in the urine of CAD patients

Methods

Sixty-five individuals (18–75 years) who underwent cardiac catheterism (CATH) were included. Random midstream urine samples were collected immediately before CATH. Patients were classified in two groups according to the presence of coronary lesions: CAD (43 patients) and non-CAD (22 patients). hK1 amidase activity was estimated using the chromogenic substrate D-Val-Leu-Arg-Nan. Creatinine was determined using Jaffé’s method. Urinary hK1-specific amidase activity was expressed as µM/(min · mg creatinine) to correct for differences in urine flow rates.

Results

Urinary hK1-specific amidase activity levels were similar between CAD [0.146 µM/(min ·mg creatinine)] and non-CAD [0.189 µM/(min . mg creatinine)] patients (p = 0.803) and remained similar to values previously reported for hypertensive patients [0.210 µM/(min . mg creatinine)] and HF patients [0.104 µM/(min . mg creatinine)]. CAD severity and hypertension were not observed to significantly affect urinary hK1-specific amidase activity.

Conclusion

CAD patients had low levels of urinary hK1-specific amidase activity, suggesting that renal KKS activity may be reduced in patients with this disease.     

Higher effective oronasal versus nasal continuous positive airway pressure in obstructive sleep apnea: Effect of mandibular stabilization

BACKGROUND:

In some individuals with obstructive sleep apnea (OSA), oronasal continuous positive airway pressure (CPAP) leads to poorer OSA correction than nasal CPAP. The authors hypothesized that this results from posterior mandibular displacement caused by the oronasal mask.

OBJECTIVE:

To test this hypothesis using a mandibular advancement device (MAD) for mandibular stabilization.

METHODS:

Subjects whose OSA was not adequately corrected by oronasal CPAP at pressures for which nasal CPAP was effective were identified. These subjects underwent polysomnography (PSG) CPAP titration with each nasal and oronasal mask consecutively, with esophageal pressure and leak monitoring, to obtain the effective pressure (Peff) of CPAP for correcting obstructive events with each mask (maximum 20 cmH₂O). PSG titration was repeated using a MAD in the neutral position. Cephalometry was performed.

RESULTS:

Six subjects with mean (± SD) nasal Peff 10.4±3.0 cmH₂O were studied. Oronasal Peff was greater than nasal Peff in all subjects, with obstructive events persisting at 20 cmH₂O by oronasal mask in four cases. This was not due to excessive leak. With the MAD, oronasal Peff was reduced in three subjects, and Peff <20 cmH₂O could be obtained in two of the four subjects with Peff >20 cmH₂O by oronasal mask alone. Subjects’ cephalometric variables were similar to published norms.

CONCLUSION:

In subjects with OSA with higher oronasal than nasal Peff, this is partially explained by posterior mandibular displacement caused by the oronasal mask. Combination treatment with oronasal mask and MAD may be useful in some individuals if a nasal mask is not tolerated.